Unified description of 2+_1 states within the deformed quasiparticle random-phase approximation

We describe low-lying collective states in deformed even-even nuclei within a deformed quasiparticle randomphase approximation (dQRPA) by using a single-particle basis with good angular momentum. The statistical factors, accounting for the level occupancy, appear in the dQRPA in a natural way as rotation coefficients that take the intrinsic system to the laboratory system. We have used our model by performing a systematic analysis of E2 transitions from the first 2+ state to the ground state for all superfluid nuclei in the range 50 < Z 100 by using a common charge polarization parameter χ = 0.2. In spite of its similarity to the QRPA, this method is able to describe in an unified way gross features of electromagnetic transitions from vibrational to rotational nuclei.